International photographer (Jan-Dec 1941)

Incorporated in one printing head is a novel, ium-slip film movement, a selection of filters for ultraviolet or fine-grain negative printing at the turning of a dial, accurate regulation of light I over a scale nearly three times as broad as previous printers, and equipment for variable density printing. Negative and positive weave is limited to ipO.OOl inch, the negative setting being adjustable to take care of negative shrinkage. Operating at nearly twice the speed of previous printers, four of the new machines provide adequate seri vice with ten companies shooting and three or i more pictures in the clubbing and release stages. Some Equipment Problems of the Direct 16-mm Producer; Loyd Thompson, The Calvin Co.. Kansas City, Mo. The increased use of direct 16-mrn. production for industrial and educational use has caused a '■ need for more and better equipment. A great deal I of the 16-mm equipment on the open market has i been designed for amateur use. Most of this equipment gives perfectly satisfactory service even [ when used for industrial purposes. However, much of it could be redesigned and built better j so that it would stand up under hard use and ; would also allow the user to work faster and ' easier. A limited survey was made among the 16-mm film producers to find what was most ■ wanted in 16-mm equipment and film. Some sug! gestions are made for improvements in film stocks, cameras, and sound-recording and projection ' equipment. Improvements are also suggested for 16-mm. laboratory service. Some Recent Advances in the Photographic Process; C. E. K. Mees, Eastman Kodak i Company, Rochester, N. Y. A popular discussion of recent advances in our 1 knowledge of what happens when photographic materials are exposed and developed. The Stereophonic Sound-Film System — General Principles; Harvey Fletcher and E. C. Wente, Bell Telephone Laboratories, New York, i N. Y. The general requirements are discussed for an ideal recording-reproducing system as determined by the characteristics of hearing of a typical group of persons listening in a typical concert hall or theater. Quantitative values are set down as ideal objectives. Although microphones, loud speakers, i and amplifiers which had been developed for the stereophonic transmission system were available for meeting these objectives, no recording medium was known which would record the wide dynamic range of intensity levels which the objectives indicated was necessary. However, this wide intensity range objective was met by using a compandor in the electrical system. A general discussion is given of the reasons for choosing the particular compandor used, for using variablearea rather than variable-density on the recorded film, for using three instead of a greater or lesser number of channels. A general description of the stereophonic sound-film system is given, including the enhancement feature. This feature makes it possible to re-record from the original recording, at the same time making any desirable changes in the dynamic range or frequency response in each of the three channels. Mechanical and Optical Equipment for the Stereophonic Sound-Film System; E. C. Wente, R. Biddulph, L. A. Elmer, and A. B. Anderson, Bell Telephone Laboratories, New York, N. Y. The same mechanism is employed for propelling the film in both recording and reproducing. To permit recording of the longer orchestral selections without interruption, the machines are designed to handle film in 2,000-ft. lengths. Special features of the film-propulsion system for obtaining great uniformity of speed at the translation points are described. The three signal and one control-channel currents are recorded by means of light-valves of identical construction. All four tracks are exposed while the film is passing over a free-running supporting roller, mounted on the same shaft with a new type of internally damped impedance roller. In reproduction, each track is exposed through an objective of high aperture to light from an incandescent source. After passing through the film, the light from each track is carried by a glass rod to a photoelectric cell. The Stereophonic Sound-Film System — Theory and Performance of Compandor Systems; Harvey Fletcher and W. B. Snow, Bell Telephone Laboratories, New York, N. Y. The general theory of compandor systems is developed and shows that the intensity level of a group of signals can be compressed and then expanded without distorting the signals. It indicates the conditions necessary for obtaining this result. Various types of compandor systems ap■( Continued on page 18) Motion Picture Equipment Studio and Laboratory Tested Since 1929 AUTOMATIC DEVELOPING MACHINE COMPLETE IN EVERY DETAIL LABORATORY EQUIPMENT WILL BE ON DISPLAY AT THE NEW SHOW ROOM, IN CONNECTION WITH MY New Address: 1515 Cahuenga Blvd. Hollywood, California ART REEVES Cable address: ARTREEVES EASTERN HEADQUARTERS for the CAMERAMAN Professional Studio & Cutting Room Equipment Always Available BELL & HOWELL MITCHELL WALL Standard, Hi-Speed, Process Standard, Hi-Speed, Silenced Latest Model Single System and Eyemo Cameras and NC Cameras Sound Cameras WE SPECIALIZE in REPAIR WORK on MITCHELL and BELL & HOWELL CAMERAS Interlock, Synchronous, Hi-Speed and Variable Speed Motors with Tachometers FEARLESS BLIMPS — FEARLESS and BABY PANORAM DOLLYS 35 mm. Double System Recording Equipment COOKE SPEED PANCHRO and ASTRO PAN TACHAR LENSES— all focal lengths MOVIOLAS SYNCHRONIZERS REWINDS TRIPODS FRANK-ZUCKER CABLE ADDRESS. CINEQUIP ^^ rn«^-tj^,:r CABLE ADDRESS. CI N EQU I P (VAMERA equipment \S^ 16 OO BROADWAY nyc V CI.rcle 6-5080 International Photographer for May, 1941 11